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Journal of Thermal Science 2013年第5期22卷 439-446页

作者： Wei Jia huoxing liu National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics School of Energy and Power Engineering Beihang University

Generally speaking, main flow path of gas turbine is assumed to be perfect for standard 3D computation. But in real engine, the turbine annulus geometry is not completely smooth for the presence of the shroud and associated cavity near the end wall. Besides, shroud leakage flow is one of the dominant sources of secondary flow in tur- bomachinery, which not only causes a deterioration of useful work but also a penalty on turbine efficiency. It has been found that neglect shroud leakage flow makes the computed velocity profiles and loss distribution signifi- cantly different to those measured. Even so, the influence of shroud leakage flow is seldom taken into considera- tion during the routine of turbine design due to insufficient understanding of its impact on end wall flows and tur- bine performance. In order to evaluate the impact of tip shroud geometry on turbine performance, a 3D computa- tional investigation for 1.5-stage turbine with shrouded blades was performed in this paper. The following ge- ometry parameters were varied respectively：

关键词： labyrinth seal tip shroud geometry shroud leakage flow turbine performance high-loaded turbine

Numerical investigation of the interaction between upstream cavity purge flow and main flow in low aspect ratio turbine cascade

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Chinese Journal of Aeronautics 2013年第1期26卷 85-93页

作者： Jia Wei liu huoxing National Key Laboratory of Science and Technology on Aero-Engines Aero-Thermodynamics School of Energy and Power Engineering Beihang University

In modern gas turbines, rim seal located between the stator-disc and rotor-disc is used to prevent hot-gas ingestion into the inner stage-gap of high pressure turbine. However, the purge flow supplied to the cavity through the rim seal interacts with the main flow, producing additional aerodynamic loss due to the mixing process which plays a significant role in the formation, development and evolution of downstream secondary flow. In this paper, a set of cascade representative of low aspect ratio turbine is selected to numerically investigate the influence of upstream cavity purge flow on the hub secondary flow structure and aerodynamic loss. Cascade with/without upstream cavity and four different purge mass flow rates are all taken into account in this simulation. Then, a deep insight into the loss mechanism of interaction between purge flow and main flow is gained. The results show that the presence of cavity and purge flow has a significant impact on the main flow which not only changes the vortex structure in both the passage and upstream cavity, but also alters the cascade exit flow angle distribution along the spanwise. Moreover, aerodynamic loss in the cascade rises with the increase of purge flow rate while the sealing effect is also enhanced. Therefore, the effect of upstream cavity purge flow must be considered in the process of turbine aerodynamic design. What is more, it is necessary to minimize the purge flow rate in order to reduce aerodynamic loss on the premise of satisfying cooling requirements.

关键词： Aerodynamic loss Low aspect ratio Purge flow Turbine Upstream cavity

Numerical Investigation of the Interaction between Mainstream and Tip Shroud Leakage Flow in a 2-Stage Low Pressure Turbine

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Journal of Thermal Science 2014年第3期23卷 215-222页

作者： JIA Wei liu huoxing National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics School of Energy and Power Engineering Beihang University

The pressing demand for future advanced gas turbine requires to identify the losses in a turbine and to understand the physical mechanisms producing them. In low pressure turbines with shrouded blades, a large portion of these losses is generated by tip shroud leakage flow and associated interaction. For this reason, shroud leakage losses are generally grouped into the losses of leakage flow itself and the losses caused by the interaction between leakage flow and mainstream. In order to evaluate the influence of shroud leakage flow and related losses on turbine performance, computational investigations for a 2-stage low pressure turbine is presented and discussed in this paper. Three dimensional steady multistage calculations using mixing plane approach were performed including detailed tip shroud geometry. Results showed that turbines with shrouded blades have an obvious advantage over unshrouded ones in terms of aerodynamic performance. A loss mechanism breakdown analysis demonstrated that the leakage loss is the main contributor in the first stage while mixing loss dominates in the second stage. Due to the blade-to-blade pressure gradient, both inlet and exit cavity present non-uniform leakage injection and extraction. The flow in the exit cavity is filled with cavity vortex, leakage jet attached to the cavity wall and recirculation zone induced by main flow ingestion. Furthermore, radial gap and exit cavity size of tip shroud have a major effect on the yaw angle near the tip region in the main flow. Therefore, a full calculation of shroud leakage flow is necessary in turbine performance analysis and the shroud geometric features need to be considered during turbine design process.

关键词： tip shroud leakage flow entropy rise low pressure turbine aerodynamic loss

Impact of Stagger Angle Nonuniformity on Turbine Aerodynamic Performance

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Journal of Thermal Science 2010年第5期19卷 465-472页

作者： Weihao Zhang Zhengping Zou Shangneng Pan huoxing liu huoxing liu Wei Li National Key Laboratory of Science and Technology on Aero-Engines School of Jet Propulsion Beihang University Beijing 100191 China Aeroengine Numerical Simulation Research Center B eihang University Beijing 100191 China Chinese Aviation Powerplant Research Institute Zhuzhou 412002 China

The assembling error may lead to variation in stagger angles,which would affect the aerodynamic performance of the *** investigate this underlying effect,two parallel numerical experiments on two turbines with the same profile,but uniform and nonuniform vane stagger angle respectively,were conducted in both steady and unsteady *** results indicate that certain changes in the detailed flow field of the turbine occur when the stagger angles are nonuniform,further,the blade loading distribution of the vane and rotor become markedly different from that in uniform vane stagger angle *** these consequences caused by nonuniformity mentioned above enhance the unsteadiness of the flow,finally,the aerodynamic performance changes *** also shows that,compared with steady simulation,the unsteady numerical simulation is necessary in this investigation.

关键词： assembling error stagger angle nonuniformity turbine aerodynamic performance

Aerodynamics Design of Two-stage Vane-less Counter-rotating Turbinec

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Journal of Thermal Science 2011年第5期20卷 406-412页

作者： Yang Zhou huoxing liu Wei Li Jun Zeng National Key Lab. on Aero-Engines Aero-Engines Simulation Research Center Beijing Univ. of Aero. ＆ Astro. Beijing 100191 China Zhuzhou Aviation Powerplant Research Institute Zhuzhou 412002 China China Gas Turbine Establishment Chengdu 610500 China

It is one of the most efficient ways to greatly improve aero-engines' performance by utilizing vaneless counterrotating turbine(VCRT) *** supply sufficient power,VCRT turns to be high Mach number,large flow angle at high-pressure turbine(HPT) rotor exit,and low blade camber angle,which increase difficulties to turbine *** the axial velocity ratio of HPT rotor is much larger than the conventional ones,the optimal selection of VCRT velocity triangles based on theoretical analysis is developed,and how the efficiency varied by HPT stator/rotor exit flow angle is also figured *** key points to design a high efficient practicable VCRT are to select velocity triangles that are characterized by low flow coefficient,high outlet flow angle and large axial velocity ratio of HPT ***,performance comparison between convergent blade and convergent-divergent blade shows the latter is more appropriate for VCRT.

关键词： counter-rotating turbine vaneless velocity triangle aerodynamic design

Discussion on back-to-back two-stage centrifugal compressor compact design techniques

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Frontiers of Mechanical Engineering 2013年第4期8卷 390-400页

作者： Lei HUO huoxing liu School of Jet Propulsion Beihang University

Design a small flow back-to-back two-stage centrifugal compressor in the aviation turbocharger,the compressor is compact structure,small axial length,light *** parts have a great influence on their overall performance ***,the stationary part of the back-to-back two-stage centrifugal compressor should pay full attention to the diffuser,bend,return vane and volute *** also impact downstream return vane,making the flow in circumferential direction is not uniformed,and several blade angle of attack is drastically changed in downstream of the volute with the airflow can not be rotated to required *** of high-pressure rotor blades change due to non-uniformed of flow in circumferential direction,which makes individual blade load distribution changed,and affected blade passage load decreased to reduce the capability of work,the tip low speed range increases.

关键词： back-to-back two-stage centrifugal compressor design Internal flow

Micromanufacturing technologies of compact heat exchangers for hypersonic precooled airbreathing propulsion: A review

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Chinese Journal of Aeronautics 2021年第2期34卷 79-103页

作者： Bao MENG Min WAN Rui ZHAO Zhengping ZOU huoxing liu School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China School of Energy and Power Engineering Beihang UniversityBeijing 100191China

The Hypersonic Precooled Combined Cycle Engine(HPCCE), which introduces precooler into traditional hypersonic engine, is regarded as the most promising propulsion system for realizing a single-stage-to-orbit vehicle. The unique demands lead to the application of the compact heat exchangers, which can realize high thrust-to-weight ratio, sufficient specific impulse and high compression ratio. However, it is challenging to accurately manufacture the compact heat exchanger due to its extremely high heat dissipation capacity, remarkable compactness, superior adaptability and harsh operating condition. This review summarizes the precooling schemes of combined cycle propulsions and describes the demands and key issues in the fabrication of a compact heat exchanger for HPCCE. The investigation focuses on the application of various micromanufacturing methods of heat exchangers constructed from tubes of less than 1 mm in diameter and microchannels of less than 200 micrometers. Various micromanufacturing processes, which include microforming, micromachining, stereolithography, chemical etching, 3 D printing, joining and other advanced microfabricating processes, were reviewed. In addition, the technologies are compared in terms of dimensional tolerance, material compatibility, and process applicability. Furthermore, the boundaries of the micromanufacturing constraints are specified as references for the design of compact heat exchangers. Ultimately, the technological difficulties and development trends are discussed for the fabrication of compact heat exchangers for HPCCE.

关键词： Compact heat exchangers Hypersonic precooled engine Microchannels Micromanufacturing Microtube

Investigation of pressure wave behaviors in the rotational speed effects on a pressure-exchange wave rotor

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Chinese Journal of Aeronautics 2022年第5期35卷 247-259页

作者： Shining CHAN huoxing liu Hang SONG Fengchao LI Chongwen JIANG Zhenxun GAO Aircraft&Propulsion Laboratory Ningbo Institute of TechnologyBeihang UniversityNingbo 315800China National Laboratory for Computational Fluid Dynamics School of Aeronautic Science and EngineeringBeihang UniversityBeijing 100083China Research Institute of Aero-Engine Beihang UniversityBeijing 100083China AVIC CAPDI Integration Equipment Co. Ltd.Beijing 102206China Aero Engine Academy of China Beijing 101300China

A wave rotor is suitable for compact and efficient pressure-exchange between gas *** work measured the circumferential pressure distribution of the rotor/stator interfaces and utilized a CFD method to simulate the unsteady pressure *** experimental and CFD results showed some slopes in the circumferential pressure distributions,and the slopes indicated the traces of specific unsteady pressure *** traces varied regularly if the rotational speed varied within a range from-11%to+11%off the baseline value,but they were seriously disturbed if the rotational speed varied by-45%from the baseline *** verified that a pressure wave in a wave rotor tended to keep its pressure ratio and propagation velocity unchanged if the rotational speed varied by a small extent,and that the pressure wave could not keep its propagation patterns if the rotational speed varied by a large *** of the pressure wave behaviors,the wave rotor demonstrated specific regulations of the rotational speed effects on its operational states.

关键词： Experimental test Pressure exchange Pressure measurement Rotational speed Unsteady pressure wave Wave rotor

Insights into thermodynamic performance of a hypersonic precooled air-breathing engine with a complicated multi-branch closed cycle

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Chinese Journal of Aeronautics 2024年第8期37卷 106-123页

作者： Yifan WANG Zhengping ZOU Pengcheng DU Lichao YAO huoxing liu Yusen XU Research Institute of Aero-Engine Beihang UniversityBeijing 102206China National Key Laboratory of Science and Technology on Aero-Engine and Aero-Thermodynamics Beihang UniversityBeijing 102206China

An advanced precooled airbreathing engine with a closed Brayton cycle is a promising solution for high-speed propulsion,of which the Synergetic Air Breathing Rocket Engine(SABRE)is a representative *** performance of the latest SABRE-4 cycle was analyzed in this ***,a relatively complete engine performance model that considers the characteristics of turbomachinery and heat exchangers was ***,Sobol’global sensitivity analysis of key performance parameters was carried out to identify the most influential design *** specific impulses under different target specific thrusts were obtained by particle swarm optimization,of which the thermodynamic parameters corresponding to a specific thrust of 1.12 kN·s·kg^(-1)and a specific impulse of 3163 s were chosen as the design *** different control laws were analyzed in contrast,and the charge control method had the strongest ability of thrust regulation as well as maintaining a favorable specific impulse ***,working characteristics under the charge control and over a typical flight envelope were calculated,in which the average value of the maximum specific impulse was as high as 5315 *** study would help to deepen the understanding of SABRE-4 thermodynamic characteristics and other precooled airbreathing engine cycles with similar layouts.

关键词： Hypersonic Precooled airbreathing engine Thermodynamic cycle Control law Working characteristics

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波转子非定常泄漏流动机理

航空学报 2017年第5期38卷 91-104页

作者：刘琛源刘火星北京航空航天大学能源与动力工程学院北京100083

针对制约波转子性能的泄漏问题,通过提取波转子中与泄漏相关的主要流动现象并建立波转子单通道泄漏模型,对非定常泄漏流动机制进行了详细的数值研究,对本文给出的非定常泄漏损失预测模型进行了数值验证。结果表明:转子通道中存在不同程... 详细信息

针对制约波转子性能的泄漏问题,通过提取波转子中与泄漏相关的主要流动现象并建立波转子单通道泄漏模型,对非定常泄漏流动机制进行了详细的数值研究,对本文给出的非定常泄漏损失预测模型进行了数值验证。结果表明:转子通道中存在不同程度的压力波动,波动幅值与间隙宽度有关;连续反射膨胀波、周期性出现的弓形激波及其反射激波是压力波动的根本原因;间隙内部泄漏过程存在3个主要的流动阶段;泄漏过程中通道激波传播速度不变、波后时均压力不变;在一定间隙宽度范围内,激波马赫数、激波静增压比与无量纲间隙宽度均呈线性关系,当间隙宽度从0增大到0.08时,激波马赫数衰减7.3%,激波静增压比衰减10.1%;泄漏流动通过泄漏产生的主膨胀波对激波传播过程施加影响,通道激波衰减本质上是理想激波与主膨胀波叠加效应的结果;泄漏损失预测模型与数值结果吻合良好。

关键词：燃气轮机波转子单通道模型非定常泄漏流动激波